Traditionally, the majority of the research on MIMO capacity assumes
a sum power constraint (SPC) for which efficient algorithms can be
derived [1]}, [2]}, [3]}, [4]}, [5]}.
Nevertheless, solutions to SPC problems may result in nonlinear distortions
if the allocated power is beyond the power limit of one or several
power amplifiers. Towards this end, per-antenna power constraint (PAPC)
is more realistic and of particular interest[6]}, [7]}, [8]}, [9]}
.
